North Korea has held a major parade a day before the opening of the Winter Olympics in the South, in a clear warning to the United States that any act of invasion would be met with the toughest response possible.

State television broadcast recorded videos of the Thursday parade in Pyongyang’s Kim Il-sung Square, with leader of the country Kim Jong-un overseeing the extravagant event.

The parade was held after Kim accepted to dispatch a group of North Korean athletes to the Winter Olympics in the South.

He has also sent his sister, one of his senior advisers, to the games, and South Korean officials have said she would attend the kick-off ceremony Friday and then would have a luncheon with President Moon Jae-in.

Experts say Kim’s manner of dealing with the Winter Games is a sign he has become genuinely open to South Korea's rapprochement efforts.

However, Kim’s words during the Thursday parade showed that the same restraint toward the United States did not exist in principle. During the event, Kim called on the North Korean military to maintain a high level of combat readiness against the US and its allies and to prevent them from infringing upon “the republic's sacred dignity and autonomy even by 0.001 millimeters.”

Disputes between Washington and Pyongyang escalated last July when North Korea test-fired two intercontinental ballistic missiles (ICBM) that analysts say are capable of hitting targets in the US mainland. Then in August, Pyongyang carried out its sixth and most powerful nuclear test, prompting Washington to engineer some unprecedented international sanctions on the country.

North Korea has warned the US that it would respond to the crippling sanctions in due course.

During the Thursday parade, one of the country’s ICBMs, the Hwasong-15, was on display, while a variety of other missiles, including a Hwasong-12 mid-range missile that was fired over Japan two times last year, were also wheeled out.